Introduction: patients. Accordingly, doctor improves the treatment of

Introduction:
This write-up describes the realisation of
devices and techniques based on evanescent field sensing using fibre optic waveguides for mid-infrared (MIR)
absorption spectroscopy. Mid-infrared absorption spectroscopy is the most recent technique for detecting the molecular
signatures of an unknown sample using their fingerprint absorption spectroscopy. In this evanescent wave field based spectroscopic
technique, the optical waveguide can detect any analytes at very low
concentration by using their fingerprint absorption. It also provides very high
sensitivity and selectivity over a wide range of compounds. The
fundamental vibrations of bio-chemical molecules occur in the MIR region.

In this region, the magnitude of absorption
of bio-chemical molecules is stronger than their
overtone bands in the near-infrared region. In this way it has been concluded that it is suitable for
highly sensitive and specific absorption spectroscopy.

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This research work will
explore novel Mid-IR waveguide based integrated photonic devices. It will also
help to realise the photonic lab on-chip platform
for biomedical diagnostic applications. This work will also involve the
fabrication and characterisation of waveguides and waveguide based devices such
as ring resonators and Mach-Zehnder interferometer. In this work the electromagnetic modelling of these devices for optimising the
performance and for designing photomask for micro-fabrication will be optimized. The fabrication will be
carried out in our state of the art clean rooms and the characterisation will
be done at the Mid-IR lab.

 

Motivation:
There are many types of
biomedical sensors available in the world.
Those sensors are used as diagnostic tools,
which are known as the glucose sensor, home
pregnancy test, water quality control sensor, calorie management sensor. But mostly those sensors are often bulky, expensive,
time consuming and needs an expert operator. Hence
those techniques are out of reach to many number
people who are living in remote areas. This is creating a lot of problem for the critically sick
peoples who need immediate medical help. Presently, in the modern technique for
the flow of disease diagnostics includes the pile up of biological
samples as blood, urine, tissue swabs etc. from
the point of care. After that those samples has
been transported to the centralised laboratories for examining
and tests by the experts. After the reports become available, the laboratory
notifies the clinicians or patients. Accordingly, doctor improves the treatment
of the patient. This evidence based treatment takes a
lot of time mainly for the critically ill patient.

It is indispensable that maximum number of
people should have prior early warning for medical diagnostics.
Hence there is obligation for mass-producible
and handheld prolific medical biosensors which
can provide accurate and reliable information
immediately at affordable price. A medical biosensor
is characterised by many number of features such as its selectivity,
sensitivity, responsivity, precision in values,
signal stability, noise, regeneration time and lifetime, affordability,
compactness and portability.

There are array of direct and indirect
laboratory based tests are available throughout the world, which depends on the
medically advantageous biochemical analytes. A technique or a combination of
techniques can be elected or engineered that offers the customised
characteristics of a medical biosensors, which are based on a specific medical
application area. Throughout
the world there are many numbers of widely used medical diagnostics facilities
such as microscopy, chromatography, immunoassays, nucleic acid
amplification, piezoelectric sensors, electrochemical and optical. All of these have their well-recognised advantages,
disadvantages, shortcomings and future scope. The
sensitivity and calibration lags in microscopy
in medical schemes. Chromatography techniques also have highly responsive but
it requires extremely expensive medical setup. For multiplex detection the
conventional immunoassays are merely sensile but are challenging and labour
demanding. A tangled sample preparation is demanded in the nucleic acid
amplification but it provides very high
molecular meticulosity. Temperature,
Voltage and Stress limits the piezoelectric sensors. The fast response time and
sensitivity pertains in the electrochemical sensors, resulting in their high
success but for increment in selectivity they often demands the highly stable reference
electrode, accurate enzyme based transducers, isolation and purification
of bio molecules from constituents or contaminants. These
fore said techniques consume not only lot of time but also it is very expensive
and may somewhere results in mislaying of bio-chemical activities in this
scenario. Optical biomedical sensors are the recent topic among the researchers
or scientists because of its versatility. An optical biomedical sensors
provides, low-cost analysis, good sensitivity, high response time, good
portability, easy to handle, very compact in size, and remotely controllable in
nature. Optical fibre detection tools have the
versatility for integration of highly multidisciplinary approaches such as
microelectronics, biology, biotechnology and chemistry. Recent health challenges have led to depth of
research and scientific findings of ways to innovate more accurate biomedical
sensors and to improve the performances of biomedical sensing capabilities. Those devices are life-saving devices that can simply acquire and process
physiological information. They have the special
availability to
select one parameter without interfering any other parameters. There are many types of biomedical sensors such as direct/indirect,
contact/remote, invasive/non-invasive, real-time/static, and sense/actuate. Each
biomedical sensor consists of a sensing element with a physical transducer that
converts a measurand into an output signal.  Basic biomedical instrumentation system has
been shown in Fig.1.